Computer-assisted, image-guided medical and surgical navigation systems are known and used to generate images in order to guide a surgeon during a medical procedure. See, for example, U.S. Pat. Nos. 5,769,861 & 6,428,547. Such systems frequently include a tracking array that is clamped to the instrument desired to be tracked.
U.S. Pat. No. 6,190,395 (“Williams”) discloses an image guided surgery (IGS) instrument having a flexible clamping band used to attach the tracking array to the instrument tip.
U.S. Pat. No. 6,021,343 (“Foley”) discloses a tool for use in image guided surgery comprising an annular guide member having a trackable array and a drive shaft for rotating an instrument such as a screwdriver while keeping the array stationary. Foley discloses an IGS instrument comprising a drive shaft, a proximal handle, a distal instrument tip, a guide that rotates around the driver shaft, and a tracking array that is mounted on the guide. In each embodiment disclosed in Foley, the drive shaft is received within an annulus of the guide member. That is, the annulus of the guide member surrounds the drive shaft, thereby allowing the array to rotate fully around the drive shaft. Further, Foley discloses attaching the instrument to the drive shaft by a simple male-female socket arrangement, in particular, a ball-and-detent mechanism. The ball and detent feature of this socket produces considerable error in tracking because the attachment occurs on one side of the connection and so is not substantially radially uniform.
PCT Published Patent Application No. WO03-071969 (“DePuy International”) discloses a surgical instrument system includes a tool including an elongate shaft which defines the tool axis. The shaft bears a plurality of marker rings arranged in a predetermined pattern on the surface of the shaft so that they extend around the shaft axis, the marker rings identifying the tool. The system includes a device for receiving signals from the rings, and a data processor for analysing the signal from the rings and generating information relating to the identity of the tool.